Assassin (アサシン, Asashin?) is an Assassin-class Servant able to be summoned by the Ritsuka Fujimaru in the Grand Orders of Fate/Grand Order.



« The Artoria Species is like a cancer of the universe.
Someone must reap them out.
Someone must. »

(Mysterious Heroine X)
Assassin's True Name is Mysterious Heroine X (謎のヒロインX, Nazo no Hiroin?), also known as Heroine X (ヒロインX, Hiroin X?) and just X, an unknown heroine who tasked herself in eliminating Saber-class heroines during Back Alley Satsuki - Chapter Heroine Sanctuary. Bearing the code name "A-X", X was a stranger who came from the "mysterious dimension" called the Servant Universe. Seeking to accomplish her "true, dearest wish" to "defeat all Sabers", she brandished Secret-Calibur and left her home town, leaving behind an "expression full of bitterness."[2]

Even before arriving at Chaldea, she managed to save an ancient royal dynasty from a crisis, settle the internal strife of the "Mankind Integration Union", and rout invaders from another universe, but such actions were trivial enough for her to not even remember accomplishing them. She will continue to brandish her sword until her goal is completed, and can still be seen "dashing across the sea of stars" even today. No matter what, she also plans to cut down the "Golden Great Emperor Cosmo Gilgamesh."[2]

X has revealed to none that her true identity is actually Artoria Pendragon. While she believes that her "perfect disguise" has tricked everyone, it is asked that others keep the fact quiet to keep from spoiling it and also for the sake of X's own honor.[2]


« It's sticking's sticking's really sticking out. »

(Assassin's profile, on her ahoge)
Assassin's appearance is said to be of a young woman with "rough and sporty garments unseemly for Servants." Her blue muffler is a symbol of courage, and her cap is used to hide her identity and ahoge, although it sticks out of the cap.[2]


  • Annihilation List (殲滅リスト, Senmetsu Risuto?)

Although Assassin displays a "carnage mode" wagering her single holy sword on nothing but defeating all present Sabers.[2]

Mystery Heroine X's wish for the Holy Grail is the destruction of all other sabers. Or at least for them to change their class name to Attacker or Swordsman or something.


Saber Class
Artoria Lily
she opened her heart towards Saber Lily alone.[2]
Mysterious Sailor X


Fate/Grand OrderEdit

SABER WARS – Lily’s Cosmic Training – The Caliburn AwakensEdit

Salomon: The Grand Time TempleEdit

She is amongst the Servants to assist the Chaldea against Demon Gods Pillar.[3]

Musashi Trial QuestEdit


Saber Slayer: Dawn (セイバースレイヤー 黎明編, Seibā Sureiyā: Reimei-hen?) is her interlude.[4]

Saber Slayer: Clash (セイバースレイヤー 激闘編, Seibā Sureiyā: Gekitō-hei?) is her interlude.[5]

Saber Slayer: Awakening (セイバースレイヤー 覚醒編, Seibā Sureiyā: Kakusei-hen?) is her interlude.[6]

Other appearancesEdit

She appears as alternate costume of Saber in Fate/Extella.


Assassin claims to be the "definitive edition of the Saber Class", acting as an Anti-Saber Decisive Weapon (対セイバー決戦兵器, Tai-Seibā Kessen Heiki?) that "fairly and squarely performs surprise attacks as a knight." She brandishes the "mysterious magic sword" Secret-Calibur to massacre her enemies and uses her favorite ship, the Dun Stallion II (ドゥ・スタリオンⅡ, Du Sutarion II?), to travel through space.[2]

A Cosmo Reactor (コスモリアクター, Kosumo Riakutā?) allowed only to the multiplying Sabers. It is reacting to various things. Settings, for example.[1]

Her Riding ability. She can't ride every possible ride-able object, but when it comes to managing ordinary spaceships, this skill displays a terrific effect. To the point where she can warp even using a ship with no warp function.[1]

She has a EX rank Presence Concealment, but it is sealed due the user herself completely denying it.[1]

Due to a mysterious communication device, the Du Stallion can automatically provide Back-up Fire (支援砲撃, Shien Hōgeki?). In a one-on-one fight between fellow swordsmen, there are no unexplored territories nor soulful tactics.[1]

Her Instincts are considerably lower than the normal Artoria's, but only when facing a Saber, her instincts rank-up to A.[1]

Galactic Meteor Sword (銀河流星剣, Ginga Ryūsei-ken?) is a power given to Saber that can destroy even stars. Also known as the sword that absolutely kills Sabers. Its attack is super effective against Sabers, so would it be an exaggeration to say that she is the greatest Saber of all?[1]

Forms and Alternate VersionsEdit

Ultra Heroine ZEdit

Ultra Heroine Z (ウルトラヒロインZ, Urutora Hiroin Z?) is an alternate version of Mysterious Heroine X who acts as the antagonist of the "Saber Wars" event. An alternate version of Mysterious Heroine X, created by her events in the past, causing a paradox to kill her after she fulfilled her mission to kill all Sabers and thus, become the most powerful Saber in the past. Ultra Heroine Z is mostly the same as Mysterious Heroine X, but she loathes all Sabers (including Lily and especially Nero) and deems MHX a faillure as a Saber Killer for "opening herself to the enemy".


Creation and ConceptionEdit

She makes her first appearance in 2013 April Fools.

Nasu Kinoko is the scenario writer for Mysterious Heroine X in Fate/Grand Order.[1] Takashi Takeuchi is the character designer for Mysterious Heroine X.[1] BUNBUN is the character illustrator for Assassin.[1][2]


  1. 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 1.15 1.16 1.17 1.18 1.19 1.20 1.21 1.22 1.23 1.24 1.25 1.26 1.27 1.28 1.29
  2. 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 2.13 2.14 2.15 2.16 2.17 2.18 2.19 2.20 2.21 2.22 2.23 2.24 2.25 2.26 2.27 2.28 Fate/Grand Order - Mysterious Heroine X Profile, Translated by Master of Chaos.
  3. Fate/Grand Order - Salomon: The Grand Time Temple - Act 09: X / Disposal Chute Andromalius
  4. Fate/Grand Order - Mysterious Heroine X interlude 01: Saber Slayer: Dawn
  5. Fate/Grand Order - Mysterious Heroine X interlude 02: Saber Slayer: Clash
  6. Fate/Grand Order - Mysterious Heroine X interlude 03: Saber Slayer: Awakening
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